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'89 R3500 Crew Cab 2wd to 4wd conversion & beyond

Started out with 2wd TBI350 with SM465 to current 4wd with 454, 700r4, NP241
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mrk5 said:
After driving in a bunch of mag chloride on the way to the snow run, the truck needed a wash. I found this while I was spraying under the truck.

View attachment 462638

Dropping bolts out the transmission crossmember. I use grade C pinch lock nuts, so I'm surprised to see them back off.

I almost forgot about my other loose bolt story. When I shifted in to 4wd on the trail I was hearing an usual sound from the front axle. When I crawled under to investigate, I found all 4 front output flange bolts loose. :yikes: Glad I decided to suck it up and crawl under the truck in the snow.

Seems like my truck is trying to fall apart.
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Must be a long bed thing, after Moab this year mine was showing 4 threads on the cross member with fresh grade 8 hardware and Nord locks.

I came home off the mountain a mile away from the house a few years back with the drivers side hardware missing off the crossmember hanging down a good 6 inches….

No wonder I can’t seal the tcase to the trans…
 
mrk5 said:
Plus some stuff from @folkenheath
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Were you going to run the L29 on the oem black box ecm, or to the 0411 controller with a change in the crank reluctor wheel, or aftermarket controls?

I’m not sure if a Holley terminator system can be run a L29 with the 4x crank signal.
 
Man @ZooMad75 spoiling all my surprises. :rotfl: We are going to run it with a Holley Teminator X which will use the 4x crank signal to do CnP ignition. Nate already hooked me up with some coil packs.

I already have a cam and new valve springs. The other thing I need is new injectors as the factory set won't work for the power we should get out of it. From what I read the L29 injectors are junk anyway and a lot of people trade them out for some Ford application injectors.
 
mrk5 said:
Man @ZooMad75 spoiling all my surprises. :rotfl: We are going to run it with a Holley Teminator X which will use the 4x crank signal to do CnP ignition. Nate already hooked me up with some coil packs.

I already have a cam and new valve springs. The other thing I need is new injectors as the factory set won't work for the power we should get out of it. From what I read the L29 injectors are junk anyway and a lot of people trade them out for some Ford application injectors.
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Well shoot. I wasn’t trying to spoil anything. Just curious. GM did a CNP version of the L29 for a couple of years in the 3500HD gmt400 trucks. Just prior to the 8.1 hitting the ground. They did however bump it up to a 24x crank signal and ran the 0411 box. Though the RPO code changed to L21 with those changes.

My buddy Ian was building one that I was able to snag some of the L21 parts while I was at the dealer. Reluctor wheel was one thing, the valve covers were the other. They looked like normal cast aluminum L29 covers but had the bosses cast in for the coil mounts. They are not the same as 8.1 covers even though the bolt pattern and shape are identical. 8.1 covers are shallow as the sealing rail is taller on the 8.1 head than a 7.4. So the 8.1 covers won’t clear the stock valvetrain. You can use L29 covers on an 8.1 since they are taller.

Still I’m curious how the terminator is going to run the coils with the 4x signal. Is it going to fire the coils sequential or just batch fire them bank to bank?
 
I've been meaning to ask @folkenheath how the firing will work with the 4x crank. The cam is just 1x.

Ironically I have an L21 right here in the shop. However it is currently employed motivating our Skyhook crane truck. I keep thinking about if there is some way it could suddenly become obsolete and need to be scrapped. :whistle: :haha:

I actually have a set of L21 valve covers sitting in the "save for later" in my eBay cart. I thought about trying to come up with some sort of clever way to mount the coils, but I kinda like having them in the traditional location so people can be confused about what engine I have. I imagine people asking:
Is that a 6.0L?​
Wait, no it's too big and the intake isn't right...​
Is it an 8.1L?​
But no, the intake isn't right for that either...​

At least it's fun to imagine even if it doesn't ever happen. :rotfl:
 
mrk5 said:
I've been meaning to ask @folkenheath how the firing will work with the 4x crank. The cam is just 1x.

Ironically I have an L21 right here in the shop. However it is currently employed motivating our Skyhook crane truck. I keep thinking about if there is some way it could suddenly become obsolete and need to be scrapped. :whistle: :haha:

I actually have a set of L21 valve covers sitting in the "save for later" in my eBay cart. I thought about trying to come up with some sort of clever way to mount the coils, but I kinda like having them in the traditional location so people can be confused about what engine I have. I imagine people asking:
Is that a 6.0L?​
Wait, no it's too big and the intake isn't right...​
Is it an 8.1L?​
But no, the intake isn't right for that either...​

At least it's fun to imagine even if it doesn't ever happen. :rotfl:
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I like the messing with people’s minds part. Nobody short of full blown gm truck nerds like us even know the L21 exists. It’s the missing link between conventional big blocks and the swan song 8.1.

Buy the covers. Those are a rare as teeth from a dodo bird. Short of robbing them from your bucket truck you probably won’t see much come up for sale.
 
mrk5 said:
I've been meaning to ask @folkenheath how the firing will work with the 4x crank. The cam is just 1x.

Ironically I have an L21 right here in the shop. However it is currently employed motivating our Skyhook crane truck. I keep thinking about if there is some way it could suddenly become obsolete and need to be scrapped. :whistle: :haha:

I actually have a set of L21 valve covers sitting in the "save for later" in my eBay cart. I thought about trying to come up with some sort of clever way to mount the coils, but I kinda like having them in the traditional location so people can be confused about what engine I have. I imagine people asking:
Is that a 6.0L?
Wait, no it's too big and the intake isn't right...
Is it an 8.1L?
But no, the intake isn't right for that either...

At least it's fun to imagine even if it doesn't ever happen. :rotfl:
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I've had people do that to my BBC Regal engine, I welded coil mounting bosses to cast big block valve covers for CnP. And I have had people ask, "what engine is that?"

The Holley can run CnP with a 4x crank and a 1x cam signal, that's the minimum you need to run it. What they were going for with a lot of the new stuff is they wanted to be able to start it faster. With the 4x you need to wait until you get the cam signal change to spark it, which depending on the ECU could be up to 2 revolutions if you are only looking for a digital rise or something. If you look for rise or fall then you can start quicker, down to 1 revolution max, but depending on the sensor you can't always trust both edges of the tooth reading, so it was safer to wait until you see the more reliable one. Now with the 24x (and 58x) they know where they are much sooner so you don't have to keep cranking to fire it.

Also, when they added VVT they needed a way to know exactly where the cam is when they move it, which is where the 58x really came into play with the additional cam sprocket targets. But you don't have to worry about that.

The racing world has been using 4 magnet crank triggers to spin over 10K RPM for decades, 4X is plenty accurate, you well still get better timing than a distributor which adds all the tolerances of the distributor gears, backlash, cam timing, cam flex, distributor tolerances, etc. With targets mounted directly on the crank the timing can be rock solid.
 
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Thanks for the explanation. Knowing how some L29 guys (online guys) were tripping over themselves to get away from the 4x crank signal I was wondering what some of the issue was. Really I think the biggest thing is getting away from the earlier “black box” ecm that most of the aftermarket tuning software companies like EFI live or hp tuners don’t have any ability to communicate with it. So if you don’t want to go with a Holley terminator setup and want a gm ecm you have to at least get to the 0411 controller and that forces the 24x crank signal.

The terminator just sounds like an easier deal all the way as it looks to be more user friendly to a tuning noob over HPT or EFIL.
 
mrk5 said:
Man @ZooMad75 spoiling all my surprises. :rotfl: We are going to run it with a Holley Teminator X which will use the 4x crank signal to do CnP ignition. Nate already hooked me up with some coil packs.

I already have a cam and new valve springs. The other thing I need is new injectors as the factory set won't work for the power we should get out of it. From what I read the L29 injectors are junk anyway and a lot of people trade them out for some Ford application injectors.
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DANG! this is exactly what I want to build for my truck!
 
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